It is proposed to continue studies on the isolation of transverse tubules and caveolae from skeletal muscle. The identification of subcellular organelles will be effected by employing external membrane markers in intact and detubulated fibers of frog sartomius followed by homogenization and fractionation of the muscle. Studies will continue concerning the presence of biochemical and physiological processes in the isolated vesicles with particular emphasis on the Ca stimulated and Na-K stimulated ATPase. Proteins will be fractionated from the membranes and purified by conventional techniques.